1. Field of the Invention
The present invention relates generally to a bag opening method and more particularly to a plastic bag opening method for opening plastic bags, one by one, where each of the bags has one edge of its opening portion elongated, the edge so elongated is provided with two pin holes and a multiplicity of the bags are held together in a multi-layer state with a pin being inserted into the pin holes.
2. Description of the Prior Art
In a packaging device for making packages by filling goods in plastic bags for packaging purpose, it is necessary to open the bags, one by one, out of a multiplicity of the bags held together in a multi-layer state. In order to facilitate operation to open the bags, one by one, out of the multi-layered bags for packaging purpose, it is so done conventionally, as shown in FIG. 5, that a bag 01 is formed having one edge 02 of its opening portion elongated, the edge 02 so elongated is provided with two pin holes 03, a pin 04 is inserted into the pin holes 03 so that a multiplicity of the bags 01 are held together in a multi-layer state and the bags 01 in the multi-layer state are opened, one by one, so that goods may be filled therein.
When the bags 01 held with the pin 04 being inserted into the pin holes 03, as shown in FIG. 5, are opened, one by one, to be used for packaging, each of the bags 01 so opened must be released from the pin 04. Conventionally, it is so done that while the pin 04 is inserted into the pin holes 03, goods are filled in the bag 01 and the bag 01 at the portion of the pin holes 03 is torn off by a force acting at the time of packaging or the like.
In this case, even though the bag 01 is torn off at the portion of the pin holes 03, as the plastic bag or the like has a considerable tensile strength, there is provided a perforated line or cut portion 05 in the portion of the pin holes 03 so that the bag 01 may be torn off easily at the portion of the pin holes 03. But, if the perforated line or cut portion 05 is made excessively, the bag 01 will be immediately torn off so that goods filling operation may be obstructed, or if the perforated line or cut portion 05 is made insufficiently, the bag 01 will be hardly torn off so that goods filling operation may be also obstructed.
Thus, in the prior art where each of the bags 01 has one edge 02 of its opening portion elongated, the edge 02 is provided with the two pin holes 03 and the multiplicity of the bags 01 are held together with the pin 04 being inserted into the pin holes 03, there has been a considerable difficulty in the operation to open the bags 01, one by one, so as to fill goods therein.
Also, even if the bag 01 is torn off well at the portion of the pin holes 03, there are often remaining torn fractions in the portion of the pin holes 03 of the bag 01 so torn off and by such bag 01, no good outside appearance of the packaged commercial goods is obtained, which has been a large problem in the bag package of this type.
It is therefore an object of the present invention to provide a plastic bag opening method for opening plastic bags, one by one, without tearing them at the portion of pin holes, where each of the bags has one edge of its opening portion elongated, the edge so elongated is provided with two pin holes and a multiplicity of the bags are held together with a pin being inserted into the pin holes.
In order to attain the mentioned object, the present invention provides a plastic bag opening method for opening plastic bags, one by one, where each of the plastic bags has one edge of its opening portion elongated, the edge so elongated is provided with two pin holes and the plastic bags are held together with a pin being inserted into the pin holes, characterized in comprising steps of; causing a pin, having its upper end free, to be inserted into the pin holes so as to hold the plastic bags together; while pressing the edges so elongated of the plastic bags at a portion between the two pin holes, blowing air from obliquely above toward an opening portion of a plastic bag of the top of the plastic bags so as to form an opening of the plastic bag; and inserting an opening member into the opening of the plastic bag so as to enlarge the opening.
In the plastic bag opening method according to the present invention, where each of the plastic bags has one edge of its opening portion elongated and the edge so elongated is provided with the two pin holes, the edges of the plastic bags, lapped one on another in a multi-layer state, are pressed at the portion between the two pin holes and air is blown from obliquely above toward the opening portion of the plastic bag of the top of the multi-layered plastic bags, hence the plastic bag of the top is opened partially to form an opening as it is held in the multi-layer state.
Then, the opening member, which is enlargeable upward/downward and/or rightward/leftward, is inserted into the opening so formed to enlarge the opening and the edge so elongated on the lower side of the plastic bag is lifted up, except the portion so pressed between the two pin holes, thereby the edge at the portion of the pin holes comes out of the pin which has its upper end free.